[rahy-sin, ris-in]

noun Chemistry.

a white, poisonous, protein powder from the bean of the castor-oil plant.

Origin of ricin

1895–1900; < New Latin Ricinus name of genus, Latin: castor-oil plant
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for ricin

Contemporary Examples of ricin

Historical Examples of ricin

  • By George, though, that Paoli must be a clever one—think of his knowing about ricin.

    The Silent Bullet

    Arthur B. Reeve

British Dictionary definitions for ricin



biochem a highly toxic protein, a lectin, derived from castor-oil seeds: used in experimental cancer therapy

Word Origin for ricin

C19: from New Latin Ricinus genus name, from Latin: castor-oil plant
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for ricin

poison obtained from the castor-oil bean, 1888, from ricinus, genus name of the castor-oil plant (1694), from Latin ricinus (Pliny), of uncertain origin, perhaps the same word as ricinus "tick" (in sheep, dogs, etc.).

Online Etymology Dictionary, © 2010 Douglas Harper

ricin in Medicine


[rīsĭn, rĭsĭn]


A poisonous protein that is extracted from the castor bean and is used as a biochemical reagent.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

ricin in Science


[rīsĭn, rĭsĭn]

An extremely poisonous protein extracted from the castor bean. Ricin inhibits protein synthesis in cells, and is used as a biochemical reagent and in cancer research.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.